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Date: Tue, 8 Nov 2022 19:51:04 -0600
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Subject: Re: Slowness after 13.7 -> 14.4
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From: Ron <ronljohnsonjr@gmail.com>
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On 11/8/22 18:06, Wells Oliver wrote:
> Upgraded 13.7 to 14.4 on RDS by restoring from a snapshot and upgrading that.

Off-topic, but did you rebuild all indices with text columns?  That might 
not be relevant in RDS (who knows exactly what's underneath the hood?) but 
it might be.

> My configuration files and instance type are exactly the same. After 
> upgrading, I ran vacuumdb -Z  -j 8 and that did its thing.
> The upgraded database is slower. I'm running EXPLAIN ANALYZE for various 
> queries and it's getting to the same plan, but it's taking longer to execute.
>
> I've always felt after major upgrades there's some element to "priming the 
> database" where it seems to be much faster a few days in after broader 
> usage. I realize it sounds absurd but I'll swear by this being my 
> experience. So I'm willing to think to some degree that queries will 
> execute faster the more people use the upgraded database.
>
> Just wondering if there is anything I might specifically look at that 
> would account for some of the slowness.

https://dba.stackexchange.com/a/295145/63913

That answer is about loading the cache yourself, either the old school 
SELECT * FROM foo WHERE ... method, or using using the pg_prewarm extension.

-- 
Angular momentum makes the world go 'round.